高强韧铸造铝合金组织与性能研究

Study on the Microstructures and Mechanical Properties of High Strength and Toughness Casting Aluminum Alloy

采用正交试验研究了Cu,Mg,Mn,Zn四种元素对新型高强韧耐热Al-Si-Cu-Mg-Mn-Zn合金室温及250℃力学性能的影响规律,分析了Al-7.0Si-2.5Cu-0.5Mg-0.3Mn-0.8Zn合金铸态及热处理后试样的金相显微组织和250℃断口形貌.结果表明:Cu,Mg,Mn,Zn四种元素对Al-Si-Cu-Mg-Mn-Zn合金室温及250℃抗拉强度和延伸率的影响顺序为,Mg>Cu>Zn≥Mn,Mg和Cu是主要影响因素,Mn和Zn是次要影响因素.随着Mg含量的增加,合金室温及250℃抗拉强度升高而伸长率下降,随着Cu含量的增加,合金室温抗拉强度升高而伸长率下降,250℃抗拉强度升高而伸长率呈先升后降趋势,Zn含量的提高有利于提高合金250℃延伸率.为使合金具有良好的综合力学性能(室温及250℃),Al-Si-Cu-Mg-Mn-Zn合金的最佳质量分数为7.0%Si,2.5%Cu,0.3%Mg,0.3%Mn,0.8%Zn,且合金力学性能室温时bσ≥345 MPa,5δ≥6.0%,250℃时bσ≥220 MPa,5δ≥9.0%.

The effects of Mg, Cu, Mn and Zn on the mechanical properties of Al-7wt%Si-Cu-Mg-Mn- Zn alloys at room temperature and 250℃ have been studied by orthorhombic experimental analysis. The microstructure and the fracture appearance of Al-7Si-2. 5Cu-0. 5Mg-0. 3Mn-0. 8Zn alloy have been analyzed. The results show that the influences of Mg, Cu, Mn and Zn on tensile strength and elongation at room temperature and 250℃ can be arranged in an order of Mg）Cu）Zn≥Mn. Mg and Cu are the major effect factors, Mn and Zn are the secondary. With the increase of Mg concentration in the alloy, the alloy tensile strength at room temperature and 250℃ increases and elongation decreases respectively. Increasing Cu concentration in the alloy, the elongation at 250℃ is first increased and then decreased. With the increase of Zn concentration, the alloy elongation is increased at 250℃. To obtain the good comprehensive mechanical properties, the optimized composition of the alloy is： 7%Si, 2.5%Cu, 0. 3% Mg, 0. 3%Mn, 0.8%Zn. And the mechanical properties of the alloy can reach σb≥345 MPa,δ5≥6.0% at room temperature and σb≥230 MPa,δ5≥9.0 % at 250 ℃.